The gravitational wave background (also GWB and stochastic background) is a possible target of gravitational wave detection experiments. The detection of such a background would have a profound impact on early-universe cosmology and on high-energy physics. The emission of gravitational waves from astrophysical sources can create a stochastic background of gravitational waves. For instance, a sufficiently massive star at the final stage of its evolution will collapse to form either a black hole or a neutron star – in the rapid collapse during the final moments of an explosive supernova event, which can lead to such formations, gravitational waves may theoretically be liberated. Also, in rapidly rotating neutron stars there is a whole class of instabilities driven by the emission of gravitat